Storage tank liquid level measuring device



Dec. 4, 1951 H. A. QUIST 2,577,629

STORAGE TANK LIQUID LEVEL MEASURING DEVICE Filed May 39, 1948 3 Sheets-Sheet 1 H954 Hg. 2

INVENTOR.

HAROLD A. QUIST ATTQRNEY Dec. 4, 1951 H. A. QUIST 2,577,629

STORAGE TANK LIQUID LEVEL MEASURING DEVICE Filed May 29, 1948 3 Sheets-Sheet 2 as 2o 22% 1 39 :l X 23 45 INVENTOR. HAROLD A. QUlST ATTORNEYS H. A. QUIST STORAGE TANK LIQUID LEVEL MEASURING DEVICE Dec. 4, 1951- 3 Sheets-Sheet 3 Filed May 29, 1948 I INVENTOR. HAROLD A. QUIST ATTORNEYS Patented Dec. 4, 1951 STORAGE I IANK LIQUID ILEVEL MEASURING DEVICE w Harold A. qu istElkton, Md., assignor to sun Oil Company, Philadelphia, Pa., a. corporation of New Jersey Application May 29, 1948; Serial No. 30,039

'11 Claims. (o1. 33126.4)

This invention relates to liquid level measuring devices and particularly to those used for determining the depth of the liquid contents of large storage tanks. 1

The primary object of this invention is to provide a device which may be used to quickly and accurately determine the elevation of the level of the liquid contents with reference to afixed datum point. Y

Another object is to provide a device which will accept and retain a level of liquid equal to the depth of; immersion whereby the elevation of the liquidin which the device has been immersed may b 'quickl and accurately determined.

. Aiurther object is to provide a portable, lightweight gauge which may be carried by an operator from tank to tank and which will function accurately and quickly to determine the liquid level within the tank.

In general, the invention comprises a transparent tube having graduations thereon or associated; therewith, which is suspended by means of a flexible tape. The tape has graduations thereon as well as cleats secured thereto at regularly spaced intervals, the cleats corresponding to the graduations. The cleats may be positioned on the flexible tape at one-foot intervals.

The lower portion of the transparent tube has an.

orifice therein to permit the liquid; within the tank to enter the tube and rise to a point adjacentthe liquid level within the tank. A cage is suspended from the bottom of the tube and a float of hollow construction is mounted within the cage. A valve stem is secured to the upper portion of the float and extends upwardly therefrom, and a valve, preferably of disc type, is secured to the upper portion of the stem; The hollow float is provided with valved orifices and is constructed to act as a dash-pot for controlling the closing of the valve, so that in operation, thevalve may be opened quickly and be maintainedin its open position .for a sufficient length of time to permit the tank liquid to rise within the tube, after which the valve will be closed slowly :so that the closing of the valve will. not

disturb the liquid within the tube. The valve is closed by the float construction after the device has been partially immersed within the tank liquid, by permittingthe tank liquid to slowly enter 'the hollow float until the float is filled or substantially filled with the liquid, after which the float sinks within its cage and securely closes the valve. 7

A more specific object of the invention is, therefore, to insure a valve actuating means other suitable material which is supported at its 2 v which will operate to quickly open the valve when the device is partially immersed in the tank liquid and which will maintain the valve in an open position for a sufficient length of time to permit the liquid to rise within the device, and thereafter securely close the valve to retain the liquid within the device.

Y Other objects of the invention will be apparent from the following specification and an inspection of the drawings.

In the drawings,

Figure l is an elevation view of the assembled ullage rod,

Figure 2 is a front view of the flexible tape,

Figure 3 is a side view of the flexible tape,

Figure 4 is an elevation in section of the ullage rod valve mechanism,

Figure 5 is an enlarged elevation of the flapper valve construction, 7

Figure 6 shows a plan view of the flapper valves,

Figures '7, 8 and 9 show the operation of the ullage rod when immersed in the liquid to be measured.

Referring to Figure 1, reference numeral 20 indicates a transparent tube formed of glass or upper end by upper cap 2|. This cap is vented by hole 2 la to permit equalizing the gas pressure in tube 20 with that of the tank. A plurality of rods 22 extend from the upper cap 2| downwardly to a lower cap 23' to secure the caps and tube together. The glass tube 20 is provided with graduations 24 numbered from the bottom upward as a scale mounted'on one of the rods 22 as shown. A ring 25 is secured'to the upper cap 2| and provides a fastening means for the flexible tape 26.

The flexible tape 26 is provided with graduations numbered downwardly so that the highest graduation number is toward the securing ring on the top of the ullage rod as indicated in Figures 2 and 3. Cleats 21 are secured at regularly spaced intervals on the tape 26 and correspond to the graduations thereon.

Thedetails of the valve construction are shown by Figures 4, 5 and 6. As illustrated in Figure 4, a cylindrical cage 30, formed of any suitable material and having an open top portion, is attached to the lower cap 23 of the ullage rod by any suitable means such as the machine screws shown. The cage 30 is provided with a plurality of apertures 3| to permit the liquid in which the ullage rod is immersed to freely enter the. cage. A hollow float 35, formed preferably the float 35 and extends through an aperture 5 formed in the wall of the cage "to" maintain.

the float in proper alignment within, and relative to, the cage. to the guide stem to limit the upward move.- ment of the float within the cage.

The float 35 is provided with. a. pair of. orifices 42 formed in the bottom wall. Flap valves 43 as detailed in Figures 5 and 6 are adapted to partially close orifices 42 by including in the flap: structure 43. a smaller aperture 44. The reasoninr thisoonstructionwill beevident fromv a.-discussion of; the operation of.- the device later in thisspecification. Thevalves 43 are'mounted adjacent to one end of arms 45 which are pivotedtozthe bottom wall ofthe float 35 by means of U-shaped brackets 46. Thepivotal connections. 46: and the:- arms. 45: are. arranged under tbs -bottom oi the float-35 so that the valve 43 underlies the orifice 42 formed: in. the float and so that the orifices 44 formed in; the valve 43 are imnegistry with. the. orifices 42. It will be seen, particularly in Figure 6, that the orifices-42 are approximately; twice the diameter of the orifices 44'. fiiuiderstrapsi-fl'g securedto the bottomof float: 351limit: the-downward and lateral movement of the free ends of the: arms; 45. As the distances-from the: pivotal, connections 46 of the arms 45 to the free end of thew-arms is. greater thani-thecdistanceato the connection to the flap valve, the free ends of the arms 45 act as. a Weight to. maintain; the flap valve 43in contact withzthey-underx side; of the float 35 and. thusrestrict the orifices 42. Suitable air vents 48' are ,positionedfinvthe'top ofthe float 35; Fiona:completequnderstanding of the operation of; the: measuring: device, reference is made to Eigures; 2 and 3' which illustrate the flexible.

member which: suspends the. ullage rod, thedetails: oi whiclrhavez-beendescribed above, and Figures-1,8 and 9; whichzshow the device in operation. In takingtmeasurements' with this device the" operator: carriesthe ullage rod and tapezito the roof oral-tank such as apetroleum products storage tank'and-lowersthe ullage rod intrxztheztank; as: indicated in Figure 7. When the ullagezrodstrikesithe liquid within the; tank, the operator senses such fact through theflexib1e,-tapewbecause the weight of the device is relieved byrthesbuoyancy of theullage rod valve mechanismzin the: liquid. Datumpoint 49, which has been established; previously at a known ele-- vationwithreference to the bottom of the tank" and;the maximumheight of1the liquid, is secured on the roof of the; tankrstructure. After the ullage: rod has; contacted the. liquid thev opera- BOIFOOIltiIllIGSWOilOWGI the tape to the next, nearesticl'eat 2.1 onathetape 25-1previously-"described. The space; between the.- cleatsis: such that the graduated. scale on the ullagev rod wil1. -be equal tortheecleat intervals: on.the tape thereby insurmg: thati theexullage rod, after contact with the liquid;..-is not totally submerged-but willbe suspended: within therliquid so as: to indicate aliq- 1116;.1IB5VB1 1 within; the. space of the graduationsa.

A suitable stop 41 is. fixed -position:. shown in Figure 7.

of the scale. The support 49, now engaged by the tape 26 at a cleat 21, enables the operator to accurately measure the distance between the datum point and the bottom of the transparent tube on the ullage rod indicated as 0 by the graduated scale thereon.

The ullage rod, being zpantially. submerged at this time, is-activated asillustratedin Figures 7, 8 and 9. The tank liquid enters the cage 30 through the apertures 3| and as the liquid rises withinthe cage 38, the hollow float 35 will be caused "torise to the full limit as determined by the stop 4! on the guide rod 40 assuming the As the float rises the valve 38., through the medium of the stem 35, uncovers the tub'eorifice 39 and permits the tank liquid to rise. in the transparent tube 20. It will be noted, of course, that the stop 4| on rod 40 is positioned to prevent the top of float 35 from striking the underside of the lower cap 23, thus insuringl'a, free passageway for the tank liquid to:' flow through L the; orifice, 33- intothe tube 28'; After a short-interval of time, thetank liquidrises in tube 2E6 to a point adjacent the: liquid level within the tank as illustr-ated'in' Figure 8. During? this periodrin". which." the tank liquidis rising in: tube; 2 8,. the liquidwill also 'enter'the; orifices; Miformed initherflapivalvesr l'3s and thence. through the orifices 42 formed in thetbottomcf the; hollowfl'o'a ti 35:1. Asithe orifice 344. is quite small in diameter, the time; required'f'orthe liquid' to enter the hollowxfioat 45 is greater than thati'necessaryrfor the. tank liquid to rise to the propernh'eightzinztube 20.. After the ullage rod has: been; partially immersed. :in: the tank liquid for: a su'fiicientr length of time to fill the float 45 which is permitted'by expelling air from the floatbody throughstheapertures 48; the liquid in the float and the weight thereof will cause the flcat to drop within the cage-33* and assumethe position shown in Fi'g ure 9. Upon the=dropping of the float; the valve 33 closes the orifice 39 andflre'tains; the liquidywithinthe tube 20. Asthe sinking of th6,fi03it 35 is a. gradual action, the-closing or the valve 38' does not disturb the liquid either: within or" without the I transparent tube 2 0, thereby enabling an'accurat'e liquidlevel measurement to be :obtained. The-weight. of the columniof liquidin the tube ZO, acting on the top oii'thev'alve 3 8, and the weight: of thefloat' together with its-liquid contents acting on the valve :3 s from below; createsna sufficient pressure on: the valve toiinsureproper closing and sealing; It; s'hould b-e. noted also that the length of theevalve-stem 35ianda-therelative position of theivalvec38s tor the? lower cap 23 is such that. thevalve 38, when in :closedipositicn, and resting on": theilowerrcap-H; willnspace' the-bottom. of tliezfloat 351 from" the bottom of, the cage" 30 so that? the; free ends; of the arms. 45. do not: contact.;the.b'ottomof the cage As: aforementioned, thea-straps 4 1'? will support the free ends of 1 arms 45i=so as' t'olimit their downward and lateral movement. Thus-when tii'e'devi'ce is first in'- sertedxiin liquid; the; free ends of the arms 45 will alwaysumaintainithe: flap valves 43 in contact :withsthe bottom; of: thesfioat :35, thereby restricting the.;orificesi.=42;. Accordingly, the flap valves:43iare..a'lwayszmaintainedjin:aaclosed positiomw'hen thevliquid is" enteringthe. float 35;

After "the .-ulla-'g,e" rod:valve assumes the positionshown in; Figure: 9, in; which; "the liquid" in .the: transparent tube is retained at the proper: eleva-- tion itimay then be: withdrawn from the-tank. Asethe: rodiis; withdrawn fromxthe liquid. within:

.the tank, the liquid rapidly drains from the cage 30 through the plurality of apertures 3| and the pressure of the liquid within the hollow float-35 becomes greater than the surrounding atmospheric .pressure. 7 The internal fluid pressure within the float 35 acts upon the flap valves 43 and is suflicient to swing the arms 45 aboutpivots 45, overcoming the .weight of the free ends of the arms. As the arms are rocked, the valves 43 open, permitting the liquid within the valvebody to rapidly drain from the orifices 42. The drainin of .the cage and float body takes place ,as the operator withdraws the measuring device from the tank. The pressure of the. column of liquid above valve 38 continues to force it downward preserving the liquidlevel in transparent tube 20.

After the device has been removed from the tank, the operator'inspects the transparent tube 20 and notes the height of the column. of liquid therein and takes the necessary reading from the indicia on or associated with the tube. The operator has previously made a note of the tape reading at the particular cleat which rested upon the pre-established datum point 49, and the two readings thus obtained will give an accurate measurement of the liquid level within the tank to a fraction of an inch. Reference to a prepared table will then indicate the cubic contents of the liquid stored within the container. I

An example of the application of this device will give a clearer understanding of the apparatus already described. Let it be assumed that the full storage depth of a tank is 40 feet. The graduated tape, with cleats placed at the even foot marks, will indicate zero when the tank is empty and 40 feet when the tank is full, the graduations on the tapebeing in reverse as previously noted. If the contents of the tank registered a height of 27 feet, 8 inches, the operator would sense the ullage rod entering the liquid when the 27foot mark was the nearest cleat above the already established datum point. This would indicate that the depth of the liquid in the tank was above 27 feet with relation to the bottom of the tank. On withdrawing the ullage rod from the tank a reading of 8 inches of liquid column within the transparent tube, the graduations increasing from the bottom of the transparent tube upward, would indicate without further calculation that the liquid depth was 27 feet, 8 inches. It will therefore be understood that a minimum of calculation is required of the operator and that the device indicates the true depth of the liquid to a fraction of an inch. The slow closing feature of-the described valve mechanism disturbs the liquid within the tank to a minimum thereby insuring that the liquid column in the transparent tube is an exact measurement of the liquid elevation above the zero point on the ullage rod.

The accuracy of the device and the ease with which it can be used is readily determined from the above description In addition, the preferred embodiment illustrated is rapid in operation. Tests made of the device show that thetransparent tube will accept a column of the measured liquid equal to the depth of immersion before the valve 38 closes which requires 25 seconds. Subsequent to closing the valve, the float requires an additional 14 seconds to fill completely thereby expelling all air and insuring a tight seal. After being lifted from the liquid the flap valves operate immediately allowing the float 35 to drain completely in 19 seconds which, under normal conditions, approximates the time required to pull 6 V the ullage rod free of the tank totake the reading. I claim: 'L 1.1'A device for measuringv the liquid level in a tank comprising a transparent, graduated tube adapted to be lowered into said tank and be partially immersed in the;liquid; a valve cooperating with the lower end of said tube; means to actuate said-valve to the open position when the rodis partially immersed in the liquid permitting said liquid to rise within the transparent tube to a leveladjacent the liquid level inthe tank and thereafter to close the valve beforethe tube is removed from theliquid thereby retaining the liquid levelwithin the tube until subsequently released; said valve actuating means including a cage adjacent the lower end of said transparent tube having aplurality of apertures therein to readily admit the liquid, a hollow float movably supported within said cage and connected to operate said valve when immersed in the liquid, said float having apertures to permit a predetermined flow of liquid into the hollow interior thereof and cause the float to sink in said cage thereby closing the valve after the liquid has risen in said tube to a level adjacent the liquid level in said tank; and a flexible suspending tape having graduations thereon secured to the upper end of said transparent graduated tube, cleats mounted on said tape at regularly spaced intervals conforming to said graduations, said cleats being adaptedto contact a fixed datum point on the top of the tank and maintain said tube at a known and fixed level when the measurement is taken.-

2 A device as defined in claim 1 further characterized by means to rapidly drain said hollow float on removal from the liquid comprising a plurality of flapper valves positioned on the bottom of said float'by suspending pivot-members, the flaps of said valves having apertures of smaller area than the apertures in said hollow float with which they are registered, and guide straps depending from the bottom of said float to control the downward and lateralmovement of said flapper valves.

3. A device as defined in claim 1 wherein said hollow float includes a guide and stop projecting from the bottom thereof to limit lateral and upward movement of said float. v

4. A device for measuring the liquid level in a tank comprising an "ullage rod including a transparent tube adapted to be lowered into a tank and be partially immersed in the liquid: a graduated scale associated with said tube; a tape having graduations thereon secured adjacent to the top of said tubefor suspending the same; a valve cooperating with the bottom of said tube; and means for actuating said valve to the open position when the rod is partially immersed in the liquid to permit the liquid to 'risewithin the tube to a point adjacent the liquid level in the'tank and to thereafter close the valve before the tube is moved to retain the liquid within the tube when the rod is withdrawn from the liquid in the tank; said means including a cage mounted on said tube below said valve having a plurality of apertures for permitting the flow of liquid therein, a hollow float mounted in said cage and connected to said valve, said float being adapted to rise vertically within said cylinder when the rod is immersed in the liquid within the tank to thus open said valve, and having apertures therein to permit the liquid within the tank to slowly enter said float to fill the same with liquid and cause the float to sink in said cylinder to thereby close the valve after the liquid in said tially' .fil'lthesame. a valve cooperating. with said floatefor restricting said or-iflce and-retarding the new of liquid into said float; said float valve.- be= ing arrangedandoonstructed to open bythe fluid pressurqwithimsaidfloat when the float iswvithdrawn from theliquid level and permit rapiddrainage of theliquid-trom said float.

.6; A device .for" measuring the liquid level in: a tankcomprising a graduated tape-and suspended therefrom a graduated tube the: lower end of whichis in .free communication withthe liquid inthe tank when the device is lowered to partiallysubmerge the tube in-such liquid, a member ataflxed distance above the bottom of the tank, members on the graduated tape engageable with saidflxed member and spacedapart atinterv-als corresponding to the length of the graduated partfofthe tube so thatone of'said tape-carried members may be engagedwith thefix-ed member when' said tube' is partially submerged as above specified, a host within. the tube permeable by liquid in the tank a valve operable by said float to close liquid communication between the tank and-tube when the liquid admitted to the float reaches a givenweight, the rate of inflow of liquid to the float being so restricted as to allow the tube to be filled to the level of liquid in the tank before the valve closes by the weight of liquid in the float, upward withdrawal movement of the device above the liquid .level' in the tank allow-- ing the liquid to drain from the float while said valve, b'y' the weight of liquid in the tube and the weight of the emptied float, remains closed.

' *7; The device defined in claim 6 comprising valve mechanism adapted to throttle the inflow of liquid to the float during the flow of liquid into the tube and operable by the weight of liquid in tli'e-flbdt, as such weight increases by continuing inns-w of liquid to the neat after the first thentione'd valve is closed, to actuate said valve mechanism to allow free outflow of the liquid from the float in the upward withdrawal movement of the" device.

8. In combination, a liquid storage tank and an ull'age rod for measuring the liquid level within the tank; saidlro'd comprising a graduated transparent tube having an opening in the lower end thereof, a valve cooperating with the tube opening, and means to slowly operate said valve on entering the tank liquid; said means including a cage depending from said tul'aeadjacent the valve having a plurality of apertures therein for admission of liquid, a hollow float enclosed in thecage and cooperatively connected to' said age-fracas valve; saidfloa-t having an orificein the bottom thereof for admission of liquid; a tape having graduations thereon secured adjacent the top: of said tube for suspending. the same; cleats se cured to said tape at regularly spaced intervals conforming to the graduations thereon; and a support mounted on-the tank adapted to act as adatum point and constructed to engage the cleats on'said tape.

9; The combination as defined in claim 8 further characterized by means to control the slow entry of liquid-through the orifice in'said float comprising. a valve 'for said orifice to restrict the size thereof andr'etard the flow ofliq-uid entering. the: float..:said valve actuating. automati cally to open and permit rapid drainage of said float when: the pressure of the liquid" within the float exceeds the surrounding pressureand again closing and restricting the orifice after the-liquid has been drained therefrom.

.10 The combination as defined in claim 9 further characterized by said valve for the oriflce in said float comprising a pivoted flap valve having an aperture therein of smaller dimensions than the said float orifice, said flap valve: aperture' being in registry with said fioat orifice to retard the inward flow of liquid when said valve isseatechand a pivotal mounting projecting: from the bottom of said float supporting said flap valve in operating and registered position.

11. The combination as defined in claimv 10 further characterized by said pivoted flapvalve apertured to register with the float orifice comprising an arm having a pivotal connection between its ends to receive the pivotal mounting projecting from the float, said flap valve being secured adjacent one end of said arm on one side of said pivotal connection and-positioned to contact the bottom-of said floatand underlie said float orifice, said armbeing heavier on the end opposite said valve to maintain said valve incontact with the bottom of the float, the valve automatically responding to retard inward flow and to drain said float on variation of liquid pressure L- therein.

HAROLD A. QUIST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS FOREIGN PATENTS Country Date Austria Nov..10,-l908- Germany "-8 Apr. 13,. .1893

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